Biomedical subjects

Maya Capelson

Publications and source records attributed to Maya Capelson.

3 recordsLinked to original sources

PubMed2006

SUMO conjugation attenuates the activity of the gypsy chromatin insulator.

Chromatin insulators have been implicated in the establishment of independent gene expression domains and in the nuclear organization of chromatin. Post-translational modification of proteins by Small Ubiquitin-like Modifier (SUMO) has been reported to regulate their activity and subnuclear localization. We present evidence suggesting that two protein components of the gypsy chromatin insulator of Dorsophila melanogaster, Mod(mdg4)2.2 and CP190, are sumoylated, and that SUMO is associated with a subset of genomic insulator sites. Disruption of the SUMO conjugation pathway improves the enhancer-blocking function of a partially active insulator, indicating that SUMO modification acts to regulate negatively the activity of the gypsy insulator. Sumoylation does not affect the ability of CP190 and Mod(mdg4)2.2 to bind chromatin, but instead appears to regulate the nuclear organization of gypsy insulator complexes. The results suggest that long-range interactions of insulator proteins are inhibited by sumoylation and that the establishment of chromatin domains can be regulated by SUMO conjugation.

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PubMed2005

The ubiquitin ligase dTopors directs the nuclear organization of a chromatin insulator.

Chromatin insulators are gene regulatory elements implicated in the establishment of independent chromatin domains. The gypsy insulator of D. melanogaster confers its activity through a protein complex that consists of three known components, Su(Hw), Mod(mdg4)2.2, and CP190. We have identified a factor, Drosophila Topoisomerase I-interacting RS protein (dTopors) that interacts with the insulator protein complex and is required for gypsy insulator function. In the absence of Mod(mdg4)2.2, nuclear clustering of insulator complexes is disrupted and insulator activity is compromised. Overexpression of dTopors in the mod(mdg4)2.2 null mutant rescues insulator activity and restores the formation of nuclear insulator bodies. dTopors associates with the nuclear lamina, and mutations in lamin disrupt dTopors localization as well as nuclear organization and activity of the gypsy insulator. Thus, dTopors appears to be involved in the establishment of chromatin organization through its ability to mediate the association of insulator complexes with a fixed nuclear substrate.

Animals↗

PubMed2004

Boundary elements and nuclear organization.

Functional compartmentalization of eukaryotic genomes is thought to be necessary for the proper regulation of gene expression. Chromatin insulators or boundary elements have been implicated in the establishment of this compartmentalization, as they may be involved in creating independent chromatin domains. Recent advances in understanding the mechanisms of insulator function suggest a role for boundary elements in determining transcriptional identity of chromatin and in organizing chromatin into structural compartments within the nucleus. Insulators may thus be involved in setting up topological chromatin domains associated with particular transcriptional states.

Animals↗